FUNGI. 23 



in the late spraying of fruit, in which case the Bordeaux mixture 

 tends to spot the fruit somewhat. 



One more liquid fungicide is deserving of mention — a solution 

 of one pound of potassium sulphide in forty-five gallons of water. 

 This is a cheap fungicide and in some cases moderately effective. 

 The Bordeaux mixture, however, presents many advantages over 

 any of these fungicides. The excess of lime which it contains 

 renders it very adhesive, so that a heavy rain is necessary to wash 

 it off from the foliage, and usually three treatments only are 

 required during the season. Furthermore, the presence of lime 

 allows of the addition of arsenical insecticides, such as Paris 

 Green or London Purple ; the arsenite retains its insoluble form 

 and no burning of the leaves results, while its action as an insect- 

 icide is unimpaired, and we have a cheap and effective combined 

 fungicide and insecticide. This is not true of any solution con- 



A'-v 



Jaining ammonia. If the arsenite be added to such a solution it is 

 rendered soluble by the ammonia, and extensive damage to the 

 leaves is sure to result from its application. 



Lastly, the Bordeaux mixture presents one very peculiar 

 property. It has been repeatedly proved that if the mixture be 

 applied to potatoes, for example, the latter experience a benefit 

 over and above that caused by the prevention of the " mildew" or 

 " rot." Even when no disease is present the vigor of sprayed 

 vines is greater than that of adjacent vines which have received no 

 treatment, all the other conditions being the same for both. 

 Whether this distinctly beneficial action of the Bordeaux mixture 

 is due to a decrease in the rate of transpiration of water from the 

 leaves, caused by the presence of the copper salt, or whether the 

 land-plaster, into which the lime of the mixture is in a great 

 measure changed, acts as a fertilizer, is a question which has not 

 yet been settled ; but the fact remains as not the least of the 

 advantages obtained by the use of Bordeaux mixture as a 

 fungicide. 



Among the many fungicides which are used as powders or 

 vapors, sulphur or mixtures the basis of which is sulphur easily 

 head the list. Even for out-door work powdered sulphur is often 

 an invaluable fungicide, as, for example, in treating the leaf-blight 

 of celery, when no other fungicide seems to be quite as effective. 

 Experience has taught us to apply the sulphur to the plants on a 

 dry day in full sunshine, though it is difficult to say why the treat- 



